My ex husband cheated on me multiple times until I finally got my sh*t together and left him. I was young so it was hard.
For a long time I wished bad things for him for treating me so awfully for no fault of my own. I left him almost 7 years ago and have since remarried, but we stayed friends, strangely. I still cared about him even though I was hurt. I don't believe in karma but I do believe your negative actions will eventually replay themselves or cause you to invite negative people into your life. So for seven years I watched him go through crap relationship after crap relationship, fail at his job, get a DUI, make stupid decisions.
Funny thing is, this year he called me one day out of the blue and told me that he had been an idiot and that he was officially apologizing for treating me like crap. He said that finally realizing what he'd thrown away was the worst punishment he could ever receive. I did nothing to get revenge.....I just let him suffer with himself. No revenge needed, it sorted itself out.
Live as if you were to die tomorrow. Learn as if you were to live forever. - Mohandas Gandhi